In today's era of modern communications, a listener is often required to play back recorded audio files. For example, in telecommunication systems, a person often needs to listen to recorded voicemails. Further, mobile devices such as personal digital assistants (PDAs), portable computers, and media players (i.e. mp3 players) can replay recorded audio files with different formats from different distribution systems, i.e. the internet (emails, podcasts, etc.) and telecommunication systems.
In addition, all recorded audio files have different audio characteristics based on the environment the audio file was recorded in; and how the various distribution systems processed the audio file. As a result, different audio files have different loudness levels, gain levels across frequencies, background noise levels, signal to noise ratios, and so forth.